How to update variables that are inside a helper body in an Ember template

Imagine a property myNumber in a controller that has a different random number every second. With this template you will see this change every second:

<h4>Random number</h4>
<p></p>

However, when the number is only referenced inside a helper (e.g. #if or #each, the number is not updated anymore. This will only show the initial value:

<h4>Random number</h4>

    <p></p>

Interestingly, when you add the reference to the property back to the root of the document, the previously static numbers will now also update:

<h4>Random number</h4>
 -- Without this reference, references below won't update.

    <p></p>

How can I have myNumber inside the helpers update, without showing the number in the root of my template?

I've tried adding the reference in html comments, but that doesn't work. I assume Ember doesn't draw elements that are not in the DOM:

<h4>Random number</h4>
<!--  -->

    <p></p>

What does work is adding the value to the DOM, but hiding it. However, this is an ugly solution:

<h4>Random number</h4>
<span style="display:none">
    
</span>

    <p></p>